SRS Sensors
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THEORY
Figure 6: NDVI data collected at five minute intervals from a corn
canopy. B) Daily mean NDVI (blue circles) and smoothed daily
NDVI (red line), substantially reduce the high frequency variability
in the original NDVI time series.
1. Toward the beginning of the time series, NDVI data increase
until plateauing in early July, when canopy closure occurred.
2. There is a significant amount of high frequency variability, mak-
ing it difficult to see this pattern clearly.
3. One source of data variability is due to sun-sensor-surface ge-
ometry. A concave diurnal pattern of NDVI is normal, and is
caused by the sun moving across the sky each day (Figure 7).
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